1. Field of the Invention
This invention relates to a multiconductor flat cable connector and, more particularly, to a connector for coupling electrically conductive wires of a plurality of multiconductor flat cables to traces of a printed circuit board and to a method of fabricating such connector.
2. Description of the Background Art
The development of new electrical cables in which a large number of wires are encapsulated in a flat insulating web has produced significant advantages in computers, telecommunication devices, and the electronic industry generally. These cables are manufactured with conductors formed as fine parallel wires located on closely spaced centerlines. They may be used for transmitting electrical power or, in the alternative, electrical signals.
Along with the obvious advantages of size reduction and ease of handling the flat cables per se, such flat cables also present certain disadvantages, both mechanically and electrically. From the mechanical standpoint, the fineness of the wires and the closeness of their spacing generally increase wire handling difficulties during the coupling of the individual wires to other electrical components such as connectors. Further, since their centerline spacings are unusually small, they may not necessarily coincide with the standard centerline spacings for commonly used electrical elements. This creates interconnection problems. The development of even smaller cables with finer, more closely spaced wires, and the need for greater numbers of wires for each connector further aggravate these mechanical problems in addition to complicating the design of connectors compatible with such further miniaturized cables.
From the electrical standpoint, particularly when flat cables are used for signal transmission purposes, the closeness of wire centerlines dictates their positioning at a specific, precise, constant distance for a particular application if the accurate transmission of signals is to be accomplished. Of equal importance, when flat, multi-wire cables are terminated with connectors, such connectors must be designed for controlling the characteristic impedance of the transmitted signals while matching it to the cable as well as the electronic devices being coupled.
In past connectors, such connector devices were normally limited to 40 connections. With the advance of technology, however, customers now need connectors with greater than 40 connections. Connections numbering in excess of 100 are needed and the future is almost limitless as to the number of connections that may be utilized.
The present invention is directed to modifying known devices such as those described in U.S. Pat. No. 4,747,787, assigned to the assignee of the present invention, whereby connectors may properly position a plurality of multiconductor flat cables with great numbers of pins. The only limitation appears to be in the number of electrical cables that can be fabricated by manufacturers of the multiconductor flat cables. The industry standard is in large part due to the manufacturing capabilities of such manufacturers. The present invention is directed to coupling a plurality of multiconductor flat cables, whether of 20 or 40 wires, into a common connector to facilitate the needs of the industry.
From a structural standpoint, the key features of the present invention include mechanisms on the connector for precluding improper connection to an associated connector to thereby eliminate the possibility of improper polarization. Another feature is that forces will be applied within the connector, not only vertically or axially between the cover halves and the pin support blocks, but also horizontally to provide lateral forces which allow for the properly positioned ultrasonic welding of the support blocks to the housing halves. Another feature is the use of attachment mechanisms at the ends of the connector for retaining the connector in position on the printed circuit board. In the past, such attachment mechanisms were along the lengths of the connector, undesirably increasing the amount of area on the printed circuit board required for the coupling. An additional advantage is in the fabrication technique wherein large numbers of pins of a plurality of cables may be coupled in a high quality environment for effecting high performance characteristics with regard to impedance control, cross talk abatement, etc.
The prior art discloses many types of other connectors for coupling multiconductor flat cables to a mating connector and electronic device. Note, for example, U.S. Pat. Nos. 3,573,719 and 3,601,768 to Lightner; 4,094,566 and 4,181,384 to Dola et al.; 4,354,719 to Weidler; 4,367,909 to Shatto et al.; 4,601,527 to Lemke and 4,860,447 to Nichols et al. None, however, discloses a connector or fabrication method of use having sufficient utility for its convenient use with a plurality of multiconductor flat cables formed with conductive wires of 0.0085 inches in diameter, several times smaller than those previously employed, cables with wires of a diameter as contemplated by the present invention. Such significantly reduced wire diameter allows for the proportionate reduction in the spacing between centerlines to 0.0125 inches along with a proportionate increase in the number of wires per cable to 81 wires per linear inch. While U.S. Pat. No. 4,616,893 discloses a connector with controlled characteristic impedance between printed circuit boards, there is no prior art teaching or suggestion of releasable connectors for a plurality of flat, multi-wire, signal transmission cables with controlled impedance characteristics matching the cable, the mating connector and the electronic devices to be coupled.
It is difficult to provide for an economical termination of a large number of conductors on the precise center lines required for this connector in such a manner that the appropriate impedance and other electrical characteristics will be maintained in the connector. By using a modular configuration in which a single size module is repetitively used, significant manufacturing efficiencies can be realized. One particular problem is the difficulty in maintaining appropriate space for a large plurality of conductors and contacts positioned end to end. This problem arises because of the build up of manufacturing tolerances. This problem is not alleviated in the prior art or by separating the individual components of the assembly into modular elements, since stacking tolerances are still a problem. In a modular configuration, it still remains important to position these individual modular subassemblies within a housing in such a manner that the electrical characteristics necessary for a high speed interconnection system, such as can be achieved with this invention can be maintained. The instant invention provides a means for fabricating such an assembly.
None of these background art patents teaches or suggests the accurate, efficient, convenient, and economical connector and fabrication method as described herein. Known methods and connectors are simply lacking in one regard or another.
As illustrated by the great number of prior patents, efforts are continuously being made in an attempt to more efficiently connect electrical elements of ever decreasing size. None of these prior art efforts, however, suggests the present inventive combination of method steps and component elements arranged and configured for coupling electrical elements as disclosed and claimed herein. Prior methods and connectors do not provide the benefits attendant with the connector and method of the present invention. The present invention achieves its purposes, objectives and advantages over the prior art methods and devices through a new, useful and unobvious combination of method steps and component elements, through the use of a minimum number of functioning parts, at a reduction in cost to manufacture and operate, and through the utilization of only readily available materials and conventional components.
It is, therefore, an object of the present invention to provide an electrical connector for coupling the wires of a plurality of multiconductor flat cables with another electrical connector comprising, in combination a plurality of electrically insulating blocks; a plurality of signal contacts extending through each block, the signal contacts of each block adapted to receive the wires of one associated multiconductor flat cable; and a housing for supporting the plurality of blocks in a fixed position with respect to each other, the housing having means to releasably couple with another electrical connector.
It is a further object of the present invention to couple the wires of a plurality of multiconductor flat cables to a printed circuit board through a single connector.
It is a further object of the present invention to minimize the usage of printed circuit board space in the coupling of a connector thereto.
It is a further object of the present invention to preclude the possibility of improperly coupling connectors with respect to each other.
It is a further object of the present invention to properly position and orient components of a connector prior to their joining as by ultrasonic welding.
Lastly, it is a further object of the present invention to manufacture a connector capable of coupling a plurality of cable multiconductor flat cables to a printed circuit board.
These objects and advantages should be construed as merely illustrative of some of the more prominent features and applications of the present invention. Many other beneficial results can be attained by applying the disclosed invention in a different manner or by modifying the invention within the scope of the disclosure. Accordingly, other objects and advantages as well as a fuller understanding of the invention may be had by referring to the summary and detailed description of the preferred embodiment of the invention in addition to the scope of the invention as defined by the claims taken in conjunction with the accompanying drawings.